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PORCELAIN INLAYS 173

is used, and to a greater extent than the thinner
foil requires. It is specially valuable when, owing
to comparatively slight separation, the matrix has
to be very carefully teased out from between the
teeth, and in many large cavities it will obviate
the necessity for filling the matrix with wax to
prevent distortion.
The manner of adapting the matrix by means
of pieces of amadou, or by means of balls of wet
cotton-wool ; and the improvement of the adaptation
by then using pieces of chamois-leather, and finally
perfecting the margins with a burnisher, if necessary,
are well known. In finally burnishing the margins,
the matrix may be held in place—to prevent rock-
ing—by means of a strip of rubber-dam tightly
stretched over the side of the tooth, or a piece of
wet silk ribbon may be used.
In applying the burnisher for perfecting margins
—and this is particularly necessary if there are any
little folds or creases at the margin—it will be
found that its use stiffens the matrix, and renders it
somewhat springy. Burnishing at one part, may cause
a lifting of the matrix at another part, and no amount
of all-round burnishing will correct this. The strip
of rubber-dam, or the silk ribbon, will prevent
this to a great extent, but as it is usually necessary
to clearly see the margins, in order to accurately